1,4-Benzodiazepine derivatives

ABSTRACT

S-Triazolo (1,5-a)(1,4) benzodiazepine derivatives are produced by the following process:   Compounds (I), (IV) and (V), 4 or 5 N-oxides thereof and acid salts thereof are active central nervous system agents.

United States Patent Tawada et al.

[ June 3,1975

l ,4-BENZODIAZEPINE DERIVATIVES Inventors: Hiroyuki Tawada, Kyoto; Kanji Meguro; Yutaka Kuwada, both of Hyogo, all of Japan Takeda Chemical Industries, Ltd., Osaka, Japan Filed: Sept. 13, 1972 Appl. No.: 288,544

Related US. Application Data Division of Ser. No. 90,139, Nov. 16, 1970, Pat. No. 3,703,525.

Assignee:

Foreign Application Priority Data Nov. 15, 1969 Japan 44-91720 US. Cl. 260/239 BD; 424/244; 424/269;

260/308 R Int. Cl C07d 53/06 Field of Search 260/239 BD Primary ExaminerHenry R. Jiles Assistant Examiner-Robert T. Bond Attorney, Agent, or F irm-Wenderoth, Lind & Ponack s-Triazolo [1,5-a][1,4] benzodiazepine derivatives are produced by the following process:

ABSTRACT Compounds (I), (IV) and (V), 4 or 5 N-oxides thereof and acid salts thereof are active central nervous system agents.

8 Claims, No Drawings 1,4-BENZODIAZEPINE DERIVATIVES This is a division of application Ser. No. 90,139, filed Nov. 16, 1970, now U.S. Pat. No. 3,703,525.

This invention relates to novel and useful s-triazolo ,5-a] 1,4] benzodiazepine derivatives of the general formula wherein R is a hydrocarbon residue, R is hydrogen or lower alkyl, rings A and/or B are unsubstituted or substituted by one or more substituents from halogen, nitro, trifluoromethyl, alkyl or alkoxy, and the nitrogen atom at the 5-position is present as such or is accompanied with an oxygen atom (the 5 N-oxide), and pharmaceutically acceptable salts thereof.

This invention also relates to a novel and useful process for producing the benzodiazepine derivatives (1).

Referring to the general formula (I), as the hydrocarbon residue represented by R, there are mentioned generally alkyl and cycloalkyl, for example of up to about 8 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.-butyl, hexyl, cyclohexyl, octyl), aryl, for example monoand di-cyclic carbocyclic aryl (e.g., phenyl, naphthyl), and aralkyl, for example phenyl lower alkyl (e.g., benzyl, phenethyl). The aromatic ring of the said aryl and aralkyl may be unsubstituted or contain substituent(s), which may be exemplified by alkyl such as lower alkyl (e.g., methyl, ethyl, propyl, isopropyl), alkenyl such as lower alkenyl (e.g., vinyl, 2-propenyl, 2-butenyl), alkoxy such as lower alkoxy (e.g., methoxy, ethoxy, propoxy, isopropoxy), acylamino such as lower alkanoylamino or aroylamino (e.g., acetylamino, benzoylamino), halogen (e.g., chlorine, bromine, fluorine, iodine) or nitro.

The lower alkyl represented by R is exemplified by methyl, ethyl, propyl, isopropyl, butyl, sec.-butyl, tert.- butyl, amyl, hexyl, etc.. Both rings A and B are unsubstituted or substituted by one or more of the same or different substituents from nitro, trifluoromethyl, halogen (e.g., chlorine, fluorine, bromine, iodine), alkyl or cycloalkyl of up to 6 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert.-butyl, pentyl, hexyl, and cyclohexyl) and alkoxy of up to 4 carbon atoms (e.g., methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, tert.-butoxy).

s-Triazolo [l,5-a][ 1,4] benzodiazepine derivatives (I) can be produced by the following process:

N: NH2

ite 1 Step 2 wherein R, R and rings A and B have the same meaning as hereinbefore defined, R is lower alkyl (e.g., methyl, ethyl, propyl) and the nitrogen atom at the 4- position of formulae (II), (N) and (V) and at the 5- position of formula (I) is accompanied or unaccompanied with an oxygen atom.

STEP 1 A Z-amino-l,4-benzodiazepine derivative of the general formula (II) is reacted with an ortho ester of the general formula (Ill) to produce a 1.4-benzodiazepine of the formula (IV). Generally, the reaction smoothly proceeds on heating at a suitable temperature from about to 200C. An ortho ester of the formula (III) is generally employed in a suitable amount of more than 1 mole, usually 2-10 moles, relative to 1 mole of the starting material of the formula (II). The reaction may be carried out in the presence ofa suitable solvent having a high boiling point enough to have the reaction proceed and inert to the compounds (ll) and (Ill). As the solvent, hydrocarbons such as toluene and xylene may preferably be employed. When the ortho ester is in a form of liquid, the reaction may proceed in the ester itself. The reaction may proceed advantageously in the presence of an acid catalyst (e.g., hydrochloric acid, sulfuric acid, acetic acid). The acid catalyst may be added in a form of an acid addition salt of the compound (II).

STEP 2 Thus obtained, 1,4-benzodiazepine derivative having imido ester residue at the 2-position (IV) is allowed to react with ammonia.

The reaction may generally proceed in the presence ofa solvent at a room temperature. If desired, however, the reaction may be carried out on heating or cooling. As a solvent, alcohols (e.g., methanol, ethanol) may preferably be employed.

The above procedure gives 2-(substituted amidino), 1,4-benzodiazepinederivative of the formula (V),

which may be isolated in a desired purity by a per se conventional procedure, for example, by distillation, recrystallization, etc..

STEP 3 Thus obtained compound of the formula (V) is subjected to the cyclization reaction.

The cyclization reaction is carried out by treating the compound (V) with a suitable oxidizing agent. The oxidizing agent may, for example, be lead tetraacetate, a salt of hypohalogenous acid (e.g., sodium or potassium salt of hypochlorous acid and hypobromous acid). The amount of the oxidizing agent employed generally is from 1 to 2 mole equivalent relative to 1 mole of the compound of the general formula (V).

The cyclization reaction may usually be carried out n in the presence of a solvent. The solvent is selected depending on the kinds of oxidizing agents and of the compounds (V).

For example, when a salt of hypohalogenous acid is employed, alcohols (e.g., methanol, ethanol) are preferably employable. In case where lead tetracetate is employed, acetic acid, hydrocarbons (e.g., benzene, toluene) and a mixture thereof are preferably employable. Generally, the cyclization reaction proceeds preferably at a temperature from to 30C, but if necessary, the reaction is carried out at a temperature outside the above range.

Thus prepared s-triazolo [1,5-a] [1,4] benzodiazepine derivative of the formula (I) may be isolated in a desired purity by a per se conventional procedure (e.g. recrystallization). The compound (I) has basic nitrogen atoms, and therefore may be recovered in a form of a suitable acid salt (e.g. hydrochloride, sulfate). The above series of reactions may be carried out stepwise or at one operation.

In case where the nitrogen atom at the 5-position of the compound (I) is accompanied with an oxygen atom, the oxygen atom may be removed, if necessary, by reduction with a suitable deoxygenating agent such as phosphorus trihalide (e.g. phosphorus trichloride), or by catalytic hydrogenation.

The compound (V) may be a tautmeric form of the formula llu N}- R. (v

Bll

aniinobenzophenone with an alkyl amine, reacting thus produced Schiffs base with aminoacetonitrile, and subsequently subjecting thus obtained 2-amino-a-phenylbenzylideneaminoacetonitrile to a cyclization reaction with an acid or alkali.

The compounds (I), (IV) and (V) produced by the method of this invention and acid salts thereof are novel and have remarkable pharmacological effects on central nervous system, such as muscular relaxing, unticonvulsive, sedative and hypnotic effect and are useful as medicaments such as a muscular relaxing agent, an anticonvulsive agent, as tranquilizer and a sleepinducing agents.

The compounds (I), (IV) and (V) and acid salts thereof are employed orally or parenterally as such or, if necessary, mixed with a pharmaceutically acceptable carrier, in a suitable pharmaceutical form such as powder, pellet, tablet and injection. The administrable amount depends on kinds of compound, conditions of illness and the like, and generally ranges from about 1 to 30 milligrams per day for an adult in oral administration.

The invention will be further illustrated by the following examples, wherein part(s) means part(s) by weight unless otherwise specified, and the relation between part(s) by weight and part(s) by volume corresponds to the relation between gram(s) and milliliter(s).

EXAMPLE 1 A mixture of 2.9 parts of 2-amino-7-chloro-5-phenyl- 3H-l,4-benzodiazepine dihydrochloride and 13.7 parts of ethyl orthoacetate is stirred vigorously at 150C, whereby the crystals are dissolved within 5 minutes. The solvent is distilled off under reduced pressure. After neutralization with aqueous sodium bicarbonate solution, the mixture is extracted with chloroform. The chloroform layer is washed with water and dried over anhydrous sodium sulfate. The solvent is distilled off under reduced pressure. and the residue is dissolved in 50 parts (by volume) of 10% ammoniacal methanol. The solution is kept standing at a room temperature for about 1 hour, followed by the distillation of the solvent. The residue is treated with ethyl acetate-isopropyl ether, whereupon 2-acetoamidino-7-chloro-S-phenyl- 3H-l,4-benzodiazepine is obtained as crystals. Recrystallization from ethyl acetate gives colorless needles, melting at l74l74.5C.

Elementary analysis. Calculated for C H CIN C, 65.70; H, 4.87; N, 18.03.

Found C, 65.68; H, 4.80; N, 18.21.

EXAMPLE 2 To a solution of 2 parts of 2-acetoamidino-7-chloro- 5-phenyl-3H-l,4-benzodiazepine prepared in Example 1 in parts (by volume) of benzene is added 1.2 part (by volume) of glacial acetic acid, followed by a gradual addition of 2.9 parts of lead tetraacetate. The mixture is admixed with water after about 20 minutes. Benzene layer is collected. Water layer is further extracted with benzene. Both benzene layers are combined and washed with an aqueous sodium bicarbonate solution and water, and then dried over anhydrous sodium sulfate. The solvent is distilled off and the residue is treated with isopropyl ether, whereupon 8-chloro-2- methyl-6-phenyl-4H-s-triazolo l ,5-a][ 1,4] benzodiazepine is obtained as crystals. Recrystallization from isopropyl ether or ethyl ether gives colorless prisms, melting at 167l68C.

Elementary analysis. Calculated for C H ClN, C, 66.13; H, 4.24: N. 18.15.

Found C, 66.10; H, 4.29; N, 18.20.

Picrate: Yellow needles(recrystallization from methanol) melting point: 208209 "C.

EXAMPLE 3 Example 2.

EXAMPLE 4 A mixture of 3.43 parts of 2-amino-7-chloro-5- phenyl-3H-1,4-benzodiazepine dihydrochloride and 17.6 parts of ethyl orthopropionate is heated at 150C for 1-0 minutes, and then poured into chloroform. The mixture is washed with an aqueous sodium bicarbonate solution and water, and dried over anhydrous sodium sulfate. The solvent is distilled off under reduced pressure and the residue is dissolved in 100 parts (by volume) of ammoniacal methanol. The solution is kept standing at a room temperature for about one hour, followed by distillation of methanol. Trituration with isopropyl ether gives propionamidino-3H-l,4-benzodiazepine as 7-chloro-5-phenyl-2- crystals.

.Recrystallizationfrom isopropyl ether gives colorless crystals melting at l46147C.

Elementary analysis. Calculated for C H 'ClN, C, 66.56; H, 5.28; N, 17.25.

Found C, 66.73; H, 5.23; N, 17.62.

EXAMPLE 5 To a solution of 1.08 part of 7-chloro-5-phenyl-2- .propionamidino-3H-1,4-benzodiazepine prepared in Example 4 in 60 parts (by volume) of benzene is added 1.5 part of lead tetraacetate gradually. The mixture is stirred for about 10 minutes, followed by addition of water. Benzenelayer is treated in the same way as is described in Example 2, whereupon 8-chloro-2-ethyl-6- phenyl-4H-s-triazolo[ 1 ,5-a] 1,4]be nzodiazepine is obtained as crystals. Recrystallization from isopropyl ether-n-hexane gives colorless prisms, melting at l lO-l 12C.

Elementary analysis. Calculated for C H ClN 66.97; H, 4.68; N, 17.36.

Found C, 67.23; H, 4.71; N, 17.19.

EXAMPLE 6 To a solution of 1.6 part of 7-chloro-5-phenyl-2- propionamidino-3H-l ,4-benzodiazepine prepared in Example 4 in 40 parts (by volume) of methanol are added 15 parts (by volume) of an aqueous sodium hypochlorite solution (1.75 mole concentration) dropwise, followed by addition of .40 parts (by volume) of water after about 5 minutes. The mixture is extracted with methylene chloride. The methylene chloride layer is washed with water and dried over anhydrous sodium sulfate, and the solvent is distilled off under reduced pressure. The residue is dissolved in a small amount of ethanol. followed by addition of 0.5 part (by volume) of concentrated sulfuric acid and ether. whereupon oily substance is separated. Ether layer is removed by decantation. The oily substance is treated with ethanol. The resulting crystals are collected by filtration. washed with ether and dried, whereupon 8-chloro-2- ethyl-6-phenyl-4H-s-triazole[ 1,5-a][ 1,4] benzodiazepine sulfate is obtained as crystals.

This sulfate is neutralized with a saturated aqueous sodium bicarbonate solution and extracted with chloroform. Chloroform layer is washed with water and dried over anhydrous sodium sulfate, whereupon 8-chloro-2- ethyl-6-phenyl-4H-s-triazolo[ 1,5-

a][ 1,4]benzodiazepine is obtained as crystals in a free form. Recrystallization from isopropyl ether-n-hexane gives colorless prisms, melting at l l0-1 12.5C.

This product is identical with the product obtained in Example 5.

EXAMPLE 7 A mixture of 2.8 parts of 2-amino-7-nitro-5-phenyl- 3H-l,4-benzodiazepine and 16 parts of ethyl orthoacetate is heated at 160C for about 15 minutes and concentrated under reduced pressure. To the residue are added 100 parts (by volume) of 15% ammoniacal ethanol under ice-cooling and with stirring. After about 20 minutes, the mixture is concentrated under reduced pressure to about half a volume at a temperature of lower than 45C. Resulting crystals are collected by filtration, whereupon 2-acetoamidino-7-nitro-5-phenyl- 3H-1,4-benzodiazepine is obtained as crystals. Recrystallization from ethyl acetate gives pale yellow needles, melting at l79-180C.

Elementary analysis. Calculated for C H N O C, 63.54; H, 4.70; N, 21.80.

Found C, 63.59; H, 4.45; N, 21.89.

EXAMPLE 8 To a solution of 1.6 parts of 2-acetoamidino-7-nitro- 5-phenyl-3-H-l,4-benzodiazepine prepared in Example 7 in 50 parts (by volume) of methanol are added dropwise 10 parts (by volume) of an aqueous sodium hypochlorite solution (1.75 mole concentration) under icecooling and with stirring. After stirring for about 15 minutes, the mixture is neutralized with acetic acid and concentrated to about one third volume under reduced pressure, followed by addition of water, whereupon 2- methyl-8-nitro-6-phenyl-4H-s-triazolo 1,5- a][1,4]benzodiazepine is obtained as crystals. Recrystallization from ethyl acetate gives yellow prisms, melting at -171.5C.

Elementary analysis. Calculated for C H N O 63.94; H, 4.10, N, 21.93.

Found C, 64.09; H, 4.00, N, 22.31.

EXAMPLE 9 A mixture of 3.7 parts of 2-amino-7-chloro-5-(pmethoxyphenyl)-3H-1,4-benzodiazepine dihydrochloride and 16 parts of ethyl orthoacetate is heated at l50l60C for about 5 minutes, followed by distillation of the solvent under reduced pressure. The residue is treated with isopropyl ether, whereupon 7-chloro-2- (a-ethoxyethylidene) amino--( p-methoxyphenyl )-3H 1,4-benzodiazepine is obtained as crystals. Recrystallization from isopropyl ether gives colorless plates, melting at l42l43C.

Elementary analysis. Calculated for C H CIN O C, 64.95; H, 5.45; N, 11.36.

Found C, 64.81; H, 5.46; N, 11.39.

EXAMPLE To a solution of 3 parts of 2-amino-7-chloro-5-(pmethoxyphenyl)-3H-1,4-benzodiazepine in 50 parts (by volume) of xylene, are added 2.4 parts of ethyl orthoacetate and 1.1 part of calcium chloride. The mixture is refluxed for 1.5 hour. After cooling, calcium chloride is removed by filtration and the filtrate is concentrated to dryness under reduced pressure. The residue is treated with isopropyl ether, whereupon 7- chloro-2-(a-ethoxyethylideneamino)-5-(pmethoxyphenyl)-3H-1.4benzodiazepine is obtained as crystals. Recrystallization from isopropyl ether gives colorless plates, melting at 142-l43C.

This product is identical with the product obtained in Example 9.

EXAMPLE 1 l 3.7 Parts of 7-chloro-2-(a-ethoxyethylidene) amino- 5-( p-methoxyphenyl )-3H- 1 ,4-benzodiazepine prepared in Example 9 or 10 are added to 100 parts (by volume) of ammoniacal ethanol. After stirring for 40 minutes and then distilling off the solvent, the residue is treated with ether, whereupon 2-acetoamidino- 7-chloro-5-(p-methoxyphenyl )-3H- 1 ,4-benzodiazepine is obtained as crystals. Recrystallization from acetone gives colorless flakes, melting at 136138C.

EXAMPLE 12 To a solution of 3.4 parts of 2-acetoamidino-7- chloro-5-(p-methoxyphenyl)-3H-1,4-benzodiazepine prepared in Example 11 in 10 parts (by volume) of methanol are added dropwise parts (by volume) of an aqueous sodium hypochlorite solution (1.75 mole concentration). The mixture is stirred for about 10 minutes, followed by the distillation of methanol. The residue is admixed with water and extracted with ethyl acetate. The ethyl acetate layer is washed with water and dried over anhydrous sodium sulfate. The solvent is removed by distillation and the residue is treated with isopropyl ether to give 8-chloro-2-methyl-6-(pmethoxyphenyl)-4H-s-triazolo [1,5-a] [1,4] benzodiazepine as crystals. Recrystallization from ethyl ether gives colorless needles, melting at 148-149C.

Elementary analysis. Calculated for C H ClN O C, 63.81; H, 4.46; N, 16.54.

Found C, 63.81; H, 4.30; N, 16.88.

EXAMPLE 13 A mixture of 2.86 parts of 2-amino-7-chloro-5- phenyl-3H-1,4-benzodiazepine 4N-oxide and 16 parts of ethyl orthoacetate is heated at 150-160C for about 7 minutes, followed by distillation of the solvent under reduced pressure. The residue is dissolved in 100 parts (by volume) of 15% ammoniacal ethanol under icecooling, and the solution is kept standing forabout 15 minutes. After the reaction is finished, ethanol is distilled off under reduced pressure. The residue is treated with ethyl acetate, whereupon 2-acetoamidino-7- chloro-5-phenyl-3H-l,4-benzodiazepine 4N-oxide is obtained as crystals. Recrystallization from ethyl acetate gives colorless needles melting at 181- 182C.

Elementary analysis. Calculated for C,;H,;-,C1N,,0 C, 62.48; H. 4.63; N, 17.15.

Found C. 62.48; H, 4.58; N, 17.48.

EXAMPLE 14 To a solution of 3.27 parts of 2-acetoamidino-7- chloro-5-phenyl-3H- l ,4-benzodiazepine 4N-oxide prepared in Example l3'in parts (by volume) of methanol are added dropwise 20 parts (by volume) of an aqueous sodium hypochlorite solution 1.75 mole concentration). Afterabout 15 minutes, methanol is distilled off under reduced pressure, followed by'addition of water. The mixture is extracted with chloroform. Chloroform layer is washed with water and dried over anhydrous sodium sulfate, and then the solvent is distilled off. The residue is treated with ethyl ether, whereupon 8-chloro-2-methyl-6-phenyl-4H-s-triazolo-[ 1 ,5- a][l,4]benzodiazepine 5N-oxide is obtained as crystals. Recrystallization from acetone gives colorless prisms, melting at 22()221C.

Elementary anlysis. Calculated for C H ClN,0 C, 62.87; H, 4.03; N, 17.25.

Found C, 63.09; H, 3.91; N, 17.43.

' EXAMPLE 15 To a solution of 1.62 parts of 8-chloro-2-methyl-6- phenyl-4H-s-triazolol1,5-a][ 1 ,4]benz'odiazepine 5N- oxide in 100 parts (by volume) of chloroform is added 0.9 part (by volume) of phosphorus trichloride. After refluxing for 3 hours, the solution is neutralized with saturated aqueous sodium bicarbonate solution. Chloroform layer is washed with water and dried over anhydrous sodium sulfate, and the solvent is distilled off. Treatment of the residue with isopropyl ether gives 8- chloro-2-methyl-6 phenyl-4H-s-triazolo l ,5-a][ 1,4]- benzodiazepine as crystals. Recrystallization from ethyl ether gives colorless prisms, melting at 167169C.

This product is identical with the product obtained in Examples 2 and 3. i I

What is claimed is:

1. A member selected from the group consisting of a compound of the formula wherein R is alkyl of up to 8 carbon atoms, cyclohexyl, phenyl, naphthyl or phenyl lower alkyl, the phenyl and naphthyl rings being unsubstituted or substituted by lower alkyl, lower alkenyl, lower alkoxy, lower alkanoylamino,benzoylam-ino, halogen or nitro, R is hydrogen or lower alkyl, and rings A and B independently are unsubstitutedor substituted by one or more members of the group consisting of halogen, nitro, trifluoromethyl, alkyl of up' td""6"'-"c aiboiiatoms, cyclohexyl and wherein R is alkyl of up to 8 carbon atoms. cyclohexyl. phenyl; naphthyl or phenyl lower alkyl, the phenyl and naphthyl rings being unsubstituted or substituted by lower alkyl, lower alkenyl, lower alkoxy, lower alkanoylamino, benzoylamino, halogen or nitro, R is hydrogen or lower alkyl, R is lower alkyl, and rings A and B independently are unsubstituted or substituted by one or more members of the group consisting of halogen, nitro, trifluoromethyl, alkyl of up to 6 carbon atoms, cyclohexyl and alkoxy of up to 4 carbon atoms, a corresponding 4N-oxide thereof and a pharmaceutically acceptable acid salt thereof.

8. A compound according to claim 7, namely, 7- chloro-2-(a-ethoxyethylidene) amino-S-(pmethoxyphenyl )-3H- 1 ,4-benzodiazepine. 

1. A MEMBER SELECTED FROM THE GROUP CONSISTING OF A COMPOUND OF THE FORMULA
 1. A member selected from the group consisting of a compound of the formula
 2. A compound according to claim 1, namely, 2-acetoamidino-7-chloro-5-phenyl-3H-1,4-benzodiazepine.
 3. A compound according to claim 1, namely, 7-chloro-5-phenyl-2-propionamidino-3H-1,4-benzodiazepine.
 4. A compound according to claim 1, namely, 2-acetoamidino-7-chloro-5-(p-methoxyphenyl)-3H-1,4-benzodiazepine.
 5. A compound according to claim 1, namely, 2-acetoamidino-6-chloro-5-phenyl-3H-1,4-benzodiazepine 4N-oxide.
 6. A compound according to claim 1, namely 2-acetoamidino 7-nitro-5-phenyl-3H-1,4-benzodiazepine.
 7. A member selected from the group consisting of a compound of the formula
 7. A MEMBER SELECTED FROM THE GROUP CONSISTING OF A COMPOUND OF THE FORMULA 